A research project is proposed to determine if infection of vertebrate hosts with an arbovirus decreases defensiveness of hosts to blood-seeking mosquitoes. The host upon which a mosquito feeds is a fundamental component of arboviral vector-host transmission systems. Anything that increases the probability of mosquitoes feeding on viremic rather than non-viremic hosts will increase the probability of disease transmission by increasing the number of infected mosquitoes. An understanding of these dynamic events is basic to describing arboviral maintenance and amplification as well as attempting to control transmission to susceptible species. Published information supports the proposed research hypothesis. Mosquitoes are differentially attracted to hosts and variation occurs within and between host species in their behavioral responses to mosquitoes that attempt to feed on them. Moreover, studies with rodent malaria have shown that infected rodent hosts are significantly more susceptible to mosquito feeding at times when parasites are infective to blood-feeding mosquitoes than are non-infected rodent hosts. During the proposed experiments we will use 4 different arbovirus systems to examine the effects of arboviral infections on host anti-mosquito behavior. Experiments are designed to determine if mosquitoes blood-feed more often on arbovirus infected hosts than non-infected hosts because infection reduces the ability of hosts to behaviorally repel mosquitoes. Initial experiments will look for gross differences and identify the 2 most appropriate virus-host-mosquito systems for more detailed study. We will examine in detail the influences of host species, host age, host behavioral patterns, and mosquito density on anti-mosquito behavior. A related goal is to determine if hosts can become viremic after ingesting virus infected mosquitoes. This research will provide basic information that will improve our ability to minimize the occurrence of arboviral disease.